Polysilazane-containing composition capable of forming a dense siliceous film

ABSTRACT

The present invention provides a polysilazane-containing composition capable of forming a dense siliceous film more rapidly and at a lower temperature than known polysilazane-containing composition. In a process for forming the siliceous film, the composition comprising a polysilazane compound, a particular amine compound and a solvent is coated on a substrate and converted into a siliceous substance. The particular amine compound preferably contains two amine groups separated from each other at the distance corresponding to five C—C bonds or more, and the amine groups preferably have hydrocarbon substituent groups.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of Ser. No. 12/739,298,filed Apr. 22, 2010, which is related to International PatentApplication No. PCT/JP2008/069406 filed Oct. 27, 2008, which is relatedto Japanese Patent Application No. 2007-279374 filed Oct. 26, 2007, thecontents of which are hereby incorporated herein by reference.

TECHNICAL FIELD

This invention relates to a composition containing a polysilazanecompound. In detail, the present invention relates to apolysilazane-containing composition which can form a dense siliceousfilm more rapidly and at a lower temperature than conventionalcompositions.

BACKGROUND ART

Polysilazane compounds can be generally converted into siliceoussubstances by heating, and the obtained siliceous substances have suchexcellent insulation properties that they are practically used asmaterials of insulating films in the electrical and electronic fields.However, if the polysilazane compounds are simply used, the conversioninto the siliceous substances proceeds very slowly and needs hightemperature. Since there is thus large room for improvement, variousstudies have been carried out to overcome the problems.

In order to improve the above problems, it is proposed to reform thepolysilazane compounds themselves or to incorporate particular additivesinto polysilazane-containing compositions. For example, anN-heterocyclic compound (described in, for example, Patent document 1),an alkanol amine (described in, for example, Patent document 2) or anamine and/or acid (described in, for example, Patent document 3) isadded as the additive into a polysilazane-containing composition so thatthe composition can form a siliceous film at a low temperature. Theamine compounds described as the additives in the above documents arealso used in a composition containing a diamine compound for otherpurposes such as reducing film-roughness or avoidingcoating-ununiformity (described in, for example, Patent documents 4 and5), and further they are still also used in a composition containing apolyamine compound for the purpose of hardening epoxy resin (describedin, for example, Patent document 6).

A dense siliceous film can be obtained if the polysilazane-containingcomposition incorporating an N-heterocyclic compound additive, which isdescribed in Patent document 1, is allowed to stand for 1 week underenvironmental conditions, preferably, is fired at 150° C. or more.However, it is desired to provide a polysilazane-containing compositionwhich can favorably form a dense siliceous film more rapidly underenvironmental conditions or by firing at a lower temperature. Meanwhile,the N-heterocyclic compound is liable to have low solubility to asolvent. Accordingly, when added into the composition, theN-heterocyclic compound is generally dissolved in an organic solventhaving high dissolution capacity, namely, in an aromatic hydrocarbon.However, since the aromatic hydrocarbon is generally very volatile andhighly harmful to the human body, it is strongly required nowadays toreduce the amount in the solvent. In consideration of that, it is muchdesired to provide a polysilazane-containing composition which can forma siliceous film more rapidly and at a lower temperature and, at thesame time, which contains a small amount of aromatic hydrocarbonsolvent.

In contrast, various solvents are usable in the polysilazane-containingcomposition incorporating an amine and/or acid additive, which isdescribed in Patent document 3. However, in order to form a densesiliceous film, it is necessary to bring the composition into contactwith steam at a high temperature for a long time. This means that, inview of forming a dense siliceous film by low temperature firing underenvironmental conditions, there is still room for improvement.

Various solvents are also usable in the polysilazane-containingcomposition incorporating an alkanol amine, which is described in Patentdocument 2. Further, this composition can form a dense siliceous film bylow temperature firing. For forming a dense siliceous film, the alkanolamine additive is made to react with the polysilazane compound, andthereby the polysilazane compound is reformed into a useful substance.However, since this reaction proceeds with violent heat generation andfoaming, the alkanol amine must be diluted in a solvent and then addedgradually for a long time. Accordingly, from the viewpoints ofefficiency and cost in mass-production, there is room for improvement.

Patent documents 4 and 5 disclose a general formula representing arelatively wide scope of amine compounds. In the documents, it isdescribed that coating ununiformity can be reduced by incorporatingthose amine compounds into a polysilazane-containing composition. On theother hand, however, the documents are silent about formation of asiliceous film obtained from the polysilazane-containing composition bylow temperature firing. Further, the present inventors' study hasrevealed that any of the polysilazane-containing compositions disclosedin the documents, such as compositions incorporatinghexamethylenediamine, p-phenylenediamine, andN,N,N′,N′-tetramethylethylenediamine, cannot form a fully satisfyingsiliceous film by low temperature firing. Accordingly, it is found thatthere is still room for improvement.

[Patent document 1] Japanese Patent Laid-Open No. H11 (1999)-116815

[Patent document 2] Japanese Patent Laid-Open No. H11 (1999)-60736

[Patent document 3] Japanese Patent Laid-Open No. H9 (1997)-31333

[Patent document 4] Japanese Patent Laid-Open No. H8 (1996)-176511

[Patent document 5] Japanese Patent Laid-Open No. H8 (1996)-176512

[Patent document 6] Japanese Patent Laid-Open No. 2004-536196

[Patent document 7] Japanese Patent Publication No. S63 (1988)-16325

[Patent document 8] Japanese Patent Laid-Open No. S61 (1986)-89230

[Patent document 9] Japanese Patent Laid-Open No. S49 (1974)-69717

[Patent document 10] Japanese Patent Laid-Open No. H1 (1989)-138108

[Patent document 11] Japanese Patent Laid-Open No. H1 (1989)-138107

[Patent document 12] Japanese Patent Laid-Open No. H1 (1989)-203429

[Patent document 13] Japanese Patent Laid-Open No. H1 (1989)-203430

[Patent document 14] Japanese Patent Laid-Open No. H4 (1992)-63833

[Patent document 15] Japanese Patent Laid-Open No. H3 (1991)-320167

[Patent document 16] Japanese Patent Laid-Open No. H2 (1990)-175726

[Patent document 17] Japanese Patent Laid-Open No. H5 (1993)-86200

[Patent document 18] Japanese Patent Laid-Open No. H5 (1993)-331293

[Patent document 19] Japanese Patent Laid-Open No. H3 (1991)-31326

[Non-patent document 1] D. Seyferth et. al., Communication of Am. Cer.Soc., C-13, January 1983

[Non-patent document 2] D. Seyferth et. al., Polym. Prepr. Am. Chem.Soc., Div. Polym. Chem., 25, 10 (1984)

[Non-patent document 3] D. Seyferth et. al., Communication of Am. Cer.Soc., C-132, July 1984

DISCLOSURE OF INVENTION Problem to be Solved by the Invention

In consideration of the aforementioned problems, it is an object of thepresent invention to provide a polysilazane-containing composition whichcan form a dense siliceous film more rapidly and at a lower temperaturethan conventional compositions.

Means for Solving Problem

The present invention is featured by

a polysilazane-containing composition comprising

a polysilazane compound,

an amine compound represented by the following formula (A):

(wherein

each R^(A) independently represents hydrogen or a hydrocarbon group ofC₁ to C₃ under the condition that two R^(A)s connecting to the samenitrogen atom are not hydrogen atoms at the same time,

each of L¹ and L² independently represents —CH₂—, —NR^(A1)— (in whichR^(A1) is hydrogen or a hydrocarbon group of C₁ to C₄) or —O—,

each of p1 and p3 is independently an integer of 0 to 4, and

p2 is an integer of 1 to 4),

or the following formula (B):

(wherein

each R^(B) independently represents hydrogen or a hydrocarbon group ofC₁ to C₄, and

each of q1 and q2 is independently an integer of 1 to 4), and

a solvent capable of dissolving said polysilazane compound and saidamine compound.

The present invention is also featured by a process for forming asiliceous film, wherein the polysilazane-containing composition iscoated on a substrate and then converted into a siliceous film.

The present invention is further featured by a siliceous film formed bythe above process.

Effect of the Invention

The present invention makes it possible to form a dense siliceous filmat a lower temperature than conventional compositions, for example, atroom temperature. If heated, the composition of the present inventioncan rapidly form a dense siliceous film. Since the siliceous film can beformed at a low temperature such as room temperature, the cost ofproduction facilities can be reduced and the facilities can berelatively freely designed. The siliceous film thus formed is so densethat it can be used in the same manner as conventional siliceous films.Further, the siliceous film formed from the polysilazane-containingcomposition of the present invention is significantly superior inhardness to siliceous films formed from conventionalpolysilazane-containing compositions, and therefore it is possible tofurther develop the use thereof.

In addition, since various solvents including solvents of low volatilityare usable, the polysilazane-containing composition of the presentinvention is very favorable from the viewpoint of safety. Accordingly,the siliceous substance derived from the composition of the presentinvention is preferably used as a material of electronic parts such asan interlayer insulating film, a top-surface protective film and aprimer for protective film. Further, in the field other thanelectronics, the siliceous substance derived from the composition of thepresent invention is also useful as a protective film of base materialssuch as metals, glass and plastics.

BEST MODE FOR CARRYING OUT THE INVENTION

Amine Compound

The polysilazane-containing composition according to the presentinvention comprises a particular amine compound. The particular aminecompound used in the present invention is represented by the followingformula (A):

(wherein

each R^(A) independently represents hydrogen or a hydrocarbon group ofC₁ to C₄ under the condition that two R^(A)s connecting to the samenitrogen atom are not hydrogen atoms at the same time,

each of L¹ and L² independently represents —CH₂—, —NR^(A1)— (in whichR^(A1) is hydrogen or a hydrocarbon group of C₁ to C₄) or —O—,

each of p1 and p3 is independently an integer of 0 to 4, and p2 is aninteger of 1 to 4),

or the following formula (B):

(wherein

each R^(B) independently represents hydrogen or a hydrocarbon group ofC₁ to C₄, and

each of q1 and q2 is independently an integer of 1 to 4). The aminecompound contains two N atoms in a molecule, and they are separated fromeach other at the interval distance corresponding to almost five C—Cbonds or more. If the amine compound contains more than two N atoms, anytwo of them satisfy the above condition. Further, the N atoms arepreferably connected to short-chain hydrocarbon groups and the number ofthe hydrocarbon groups is preferably as large as possible. In otherwords, the number of N—H bonds is preferably as small as possible.However, with respect to the amine compound represented by the formula(B), the effect of the present invention can be obtained even if theterminal N atom is connected to two hydrogen atoms.

Among the above amine compounds, particularly preferred compounds arerepresented by the following formulas:

Those amine compounds can be used in combination of two or more, ifnecessary.

It is not clear how the particular amine compound defined in the presentinvention works to achieve the effect of the invention, but is presumedas follows. The amine compound defined in the present invention containsplural N atoms separated at proper distance, and hence can interact withplural Si atoms of the polysilazane compound simultaneously in thecomposition. As a result, the Si—N bonds in the polysilazane compoundare thought to be easily cleaved to promote the silica conversion.Further, since the N atoms are connected to hydrocarbon groups, thesolubility is improved and, at the same time, the electron donatingability is enhanced, so that the amine compound can readily interactwith Si atoms of the polysilazane compound. In consideration of that,the hydrocarbon group connecting to the N atom preferably contains 3 orless carbon atoms. If having a long structure, the hydrocarbon group maybe bulky enough to sterically hinder the interaction.

Polysilazane Compound

There is no particular restriction on the polysilazane compound used inthe present invention, and any polysilazane compound can be selected touse unless it impairs the effect of the invention. It may be either aninorganic polysilazane compound or an organic one. Preferred examples ofthe inorganic polysilazane compound include: a perhydropolysilazane(described in Patent document 7) which contains a straight chainstructure having a repeating unit represented by the following formula(I):

which has a molecular weight of 690 to 2000, which comprises 3 to 10SiH₃ groups in a molecule, and in which the element ratios based onchemical analysis are Si: 59 to 61, N: 31 to 34 and H, 6.5 to 7.5 interms of weight percent; and another perhydropolysilazane having apolystyrene-reduced average molecular weight of 3000 to 20000.

The above perhydropolysilazane can be synthesized according to themethods described in Patent document 7 and Non-patent document 1. Theperhydropolysilazane basically comprises a chain moiety and a cyclicmoiety, and can be represented by the formula:

The structure of perhydropolysilazane is, for example, as follows:

Other examples of the polysilazane compound include: a polysilazanewhich has a number average molecular weight of approx. 100 to 50000 andwhich has a skeleton comprising a structure unit represented by thefollowing formula (II):

(in which each of R¹, R² and R³ is independently hydrogen, an alkylgroup, an alkenyl group, a cycloalkyl group, an aryl group, analkylsilyl group, an alkylamino group, an alkoxy group, or another groupsuch as a fluoroalkyl group which contains a carbon atom directlyconnecting to the silicon atom, provided that at least one of R¹, R² andR³ is hydrogen atom); and modified compounds thereof.

For example, a polysilazane represented by the formula (II) in which R¹and R² are hydrogens and R³ is methyl can be synthesized according tothe method reported by Non-patent document 2. This method also providesa polysilazane of chain or cyclic polymer having a repeating unit—(SiH₂NCH₃)—. There is no crosslinking structure in any polysilazanecompound obtained by the method.

Further, a polyorgano(hydro)silazane represented by the formula (II) inwhich R¹ and R² are hydrogens and R³ is an organic group can besynthesized according to the method reported by Non-patent document 2 orPatent document 8. This method also provides a polysilazane of a cyclicstructure having a repeating unit —(R²SiHNH)— with a polymerizationdegree of 3 to 5 and a polysilazane which has both chain and cyclicstructures in a molecule and which is represented by the formula:(R³SiHNH)_(x)[(R²SiH)_(1.5)N]_(1-x) (0.4<x<1).

In addition, the above method also provides a polysilazane representedby the formula (II) in which R¹ is hydrogen and R² and R³ are organicgroups or in which R¹ and R² are organic groups and R³ is hydrogen. Thatpolysilazane may have a cyclic structure comprising a repeating unit—(R¹R²SiNR³)— with a polymerization degree of 3 to 5.

Organic polysilazane compounds other than the compounds represented bythe above formula (II) include: a polyorgano(hydro)silazane (describedin Non-patent document 3) having a crosslinking structure represented bythe formula:

a polysilazane R¹Si(NH)_(x) having a crosslinking structure obtained byammonolysis of R¹SiX₃ (X: halogen), and a polysilazane (described inPatent document 9) obtained by co-ammonolysis of R¹SiX₃ and R² ₂SiX₂ andrepresented by the following formula:

Examples of polysilazane compounds other than the above include: highpolymers of inorganic silazane having increased molecular weights and/orhaving improved hydrolysis resistance, reformed polysilazanes (describedin Patent documents 10 to 15), and co-polymerized silazanes (describedin Patent documents 16 to 19) which are modified to be suitable forformation of thick films by introducing organic components intopolysilazanes. These polysilazane compounds can be used in combinationof two or more.

Solvent

The composition according to the present invention comprises a solventcapable of dissolving the above polysilazane compound and the aboveamine compound. There is no particular restriction on the solvent aslong as it can dissolve the above components. Preferred examples of thesolvent include:

(a) aromatic compounds, such as benzene, toluene, xylene, ethylbenzene,diethylbenzene, trimethylbenzene and triethylbenzene; (b) saturatedhydrocarbon compounds, such as n-pentane, i-pentane, n-hexane, i-hexane,n-heptane, i-heptane, n-octane, i-octane, n-nonane, i-nonane, n-decaneand i-decane; (c) alicyclic hydrocarbon compounds, such asethylcyclohexane, methylcyclohexane, cyclohexane, cyclohexene,p-menthane, decahydronaphthalene, dipentene and limonene; (d) ethers,such as dipropyl ether, dibutyl ether, diethyl ether, methyl tertiarybutyl ether (hereinafter, referred to as MTBE) and anisole; and (e)ketones, such as methyl isobutyl ketone (hereinafter, referred to asMIBK). Among them, more preferred are (b) saturated hydrocarboncompounds, (c) alicyclic hydrocarbon compounds, (d) ethers and (e)ketones.

Those solvents can be used in combination of two or more, so as tocontrol the evaporation rate, to reduce the hazardousness to the humanbody and to control the solubility of the components.

It is also possible to use commercially available solvents as thesolvent in the present invention. Examples of the usable commerciallyavailable solvents include: Pegasol AN45 ([trademark], manufactured byExxon Mobil Corporation), which is an aliphatic/alicyclic hydrocarbonmixture containing an aromatic hydrocarbon of C8 or more in an amount of5 to 25 wt %; and Exxsol D40 ([trademark], manufactured by Exxon MobilCorporation), which is an aliphatic/alicyclic hydrocarbon mixturecontaining no aromatic hydrocarbon. If a mixture of solvents is used, itpreferably contains an aromatic hydrocarbon in an amount of 30 wt % orless based on the total weight of the mixture, in view of reducing thehazardousness to the human body.

The amine compound defined in the present invention has relatively highsolubility, and hence various solvents are usable. Accordingly, inconsideration of safety, solvents of low volatility are preferably used.Particularly preferred are solvents of low volatility selected from theabove-described examples, such as:

-   -   (b1) n-pentane, i-pentane, n-hexane, i-hexane, n-heptane,        i-heptane, n-octane, i-octane, n-nonane, i-nonane, n-decane and        i-decane;    -   (c1) ethylcyclohexane, methylcyclohexane, cyclohexane,        cyclohexane, p-menthane and dipentene;    -   (d1) dipropyl ether, dibutyl ether and MTBE; and    -   (e1) MIBK.

Further, Exxsol D40 ([trademark], manufactured by Exxon MobilCorporation), which is described above, is also preferred.

As an indicator suggesting what solvent to select and use, vaporpressure of solvent can be adopted. Considering the relation betweenvolatility and vapor pressure, solvent having a vapor pressure of 0.8kPa or less at 20° C. are preferably used. The vapor pressure is morepreferably 0.65 kPa or less, further preferably 0.5 kPa or less.Examples of those solvents include: dibutyl ether (vapor pressure at 20°C.: 0.48 kPa), Pegasol AN45 (vapor pressure at 20° C.: 0.29 kPa), ExxsolD40 (vapor pressure at 20° C.: 0.18 kPa), Certrex 60 (vapor pressure at20° C.: 0.017 kPa), and Solvesso 150 (vapor pressure at 20° C.: 0.083kPa). (Exxsol D40 and Solvesso 150, as well as Pegasol AN45 and Certrex60, are trademarks manufactured by Exxon Mobil Corporation.) Thosesolvents are less volatile than, for example, xylene (vapor pressure at20° C.: 0.87 kPa), and hence less harmful to the human body.

Other Additives

The composition according to the present invention can contain otheradditives, if necessary. Examples of the optional additives include aviscosity modifier and a crosslinking accelerator. Further, when usedfor a semiconductor devise, the composition can contain a phosphoruscompound such as tris(trimethylsilyl)phosphate for the sake ofNa-gettering effect.

Polysilazane-Containing Composition

The polysilazane-containing composition of the present inventioncomprises the above solvent in which the above polysilazane compound,the particular amine compound and other optional additives are dissolvedor dispersed. There is no particular restriction on the order ofdissolving or dispersing the components in the organic solvent. Further,the components may be beforehand reacted and then the solvent may bereplaced.

The content of the amine compound is generally 50 wt % or less,preferably 10 wt % or less based on that of the polysilazane compound.Particularly in the case where the polysilazane compound is aperhydropolysilazane in which the silicon atom is not connected to analkyl group or the like, the effect of the present invention can beobtained even if the amine compound is incorporated in a relativelysmall amount. This is because that perhydropolysilazane worksadvantageously from the electronic and stereochemical viewpoints. Inthat case, the composition preferably contains the amine compound in anamount of generally 1 to 20%, preferably 3 to 10%, more preferably 4 to8%, further preferably 4 to 6%. The content of the amine compound ispreferably more than a certain amount so that the amine compound canmaximally perform its functions such as catalyzing the reaction andimproving density of the film. On the other hand, however, it ispreferably less than another certain amount so that the composition cankeep compatibility and can form an uniform film.

The amount of each component described above depends on the use of thecomposition. However, in order to form a siliceous film havingsufficient thickness, the content of the polysilazane compound ispreferably 0.1 to 40 wt %, more preferably 0.5 to 20 wt %, and furtherpreferably 5 to 20 wt %. Normally, if containing the polysilazanecompound in an amount of 5 to 20 wt %, the composition can form a filmof generally preferred thickness, for example, of a thickness of 2000 to8000 Å.

Siliceous Film Formation Process

In the process of the present invention for forming a siliceous film,the above polysilazane-containing composition is coated on a substrateand then converted by heating, if necessary, into a siliceous film.

There is no particular restriction on what material the surface of thesubstrate is made of. The substrate may be a bare silicon wafer, or asilicon wafer coated with a thermal oxide film or with a silicon nitridefilm. If necessary, the substrate may be fabricated to form, forexample, trench isolation grooves.

The composition can be coated on the substrate according to knownmethods, such as spin coating, dip coating, spraying method, andtransferring method. Among them, spin coating is preferred.

After the composition is coated on the substrate, excess of the organicsolvent is dried (removed), if necessary, and then the polysilazanecompound in the composition is converted into a siliceous substanceunder an oxidizing atmosphere, such as an atmosphere containing steam,oxygen gas or mixture thereof. In the present invention, the conversionis preferably performed by firing under an atmosphere containing oxygengas. The content of oxygen gas is preferably 1% or more, more preferably10% or more by volume. The atmosphere may contain inert gases such asnitrogen and helium unless they impair the effect of the presentinvention.

If the conversion is performed under an atmosphere containing steam, thecontent of steam is preferably 0.1% or more, more preferably 1% or moreby volume. In the present invention, the polysilazane compound isconverted preferably by firing under an atmosphere containing both steamand oxygen gas.

It is necessary to perform the conversion at such a temperature that thepolysilazane compound can be converted into a siliceous film. Thetemperature is generally 20 to 1000° C., preferably 20 to 300° C., morepreferably 20 to 100° C. The conversion time can be properly determinedaccording to the conversion temperature, but is normally 5 minutes to 1week, preferably 15 minutes to 1 day, more preferably 15 minutes to 2hours. Under a humid atmosphere, the temperature and time required forthe conversion can be lowered and shortened, respectively. For example,if the conversion is carried out at a humidity of 70% or more, thetemperature and time required for the conversion can be lowered to 80°C. or less and shortened to 1 hour or less, respectively.

Siliceous Film and Substrate Coated with Siliceous Film

A siliceous film and a substrate coated with the siliceous film can beproduced from the aforementioned polysilazane-containing composition ofthe present invention. As long as the composition of the presentinvention is used, there is no particular restriction on the productionconditions. For example, they can be obtained in the manner describedabove. The siliceous film and the siliceous film-coated substrate can bepreferably used as electronic parts such as an interlayer insulatingfilm, a top-surface protective film and a primer for protective film.Further, in the field other than electronics, they are also useful asprotective films of surface of substrates such as made of metals, glassand plastics.

The present invention is further explained by use of the followingexamples.

SYNTHESIS EXAMPLE 1 Synthesis of Perhydropolysilazane

According to the method described in Patent document 1, aperhydropolysilazane was synthesized as follows.

A 1-L four-neck flask equipped with a gas-inlet tube, a mechanicalstirrer and a Dewar condenser was used as a reaction vessel. The vesselwas filled with a dry deoxidized nitrogen gas, and then 1500 ml of drydegassed pyridine was poured therein and cooled with ice. After that,100 g of dichlorosilane was added to the vessel, to form white solidadduct (SiH₂Cl₂.2C₅H₅N). While the reaction mixture was stirred andcooled with ice, 70 g of gaseous ammonia was bubbled therein.Subsequently, dry nitrogen gas was bubbled through the reaction liquidfor 30 minutes to remove excess of the ammonia.

The formed product was subjected to reduced pressure filtration with aBuchner funnel under an atmosphere of dry nitrogen gas, to obtain 1200ml of filtrate. From the filtrate, pyridine was distilled off by meansof an evaporator to obtain 40 g of perhydropolysilazane. The numberaverage molecular weight of the obtained perhydropolysilazane wasmeasured by GPC (developer: CDCl₃), and thereby was found to be 800 interms of polystyrene-standard. The IR spectrum thereof was alsomeasured. As a result, absorption peaks assigned to N—H at 3350 and 1200cm⁻¹, assigned to Si—H at 2170 cm⁻¹ and assigned to Si—N—Si at 1020 to820 cm⁻¹ were verified.

EXAMPLES 1 TO 11 AND COMPARATIVE EXAMPLES 1 TO 7

In a 100 ml glass beaker, 16 g of the perhydropolysilazane obtained inSynthesis Example 1 and 64 g of dibutyl ether were mixed to prepare apolysilazane solution. While the polysilazane solution was stirred witha stirrer, 0.8 g (5.0 wt % based on the perhydropolysilazane) oftetramethylhexanediamine shown in Table 1 was added to obtain apolysilazane-containing composition of Example 1. The procedure ofExample 1 was repeated except that the kind and amount of the aminecompound and the solvent were changed into those shown in Table 1, toobtain polysilazane-containing compositions of Examples 1 to 11 andComparative examples 1 to 7.

TABLE 1 Amine compound Name Structure Amount Solvent Ex. 1 tetramethyl-(A1) 5.0 dibutyl ether hexanediamine Ex. 2 bis N,N- (A2) 5.0 dibutylether dimethylamino- ethyl ether Ex. 3 1,1,4,7,10,10- (A3) 5.0 dibutylether hexamethyltri- ethylene- tetramine Ex. 4 m-xylenediamine (B1) 5.0dibutyl ether Ex. 5 iminobis N,N′- (A4) 5.0 dibutyl ether dimethyl-propylamine Ex. 6 tetramethyl- (A1) 1.0 dibutyl ether hexanediamine Ex.7 tetramethyl- (A1) 3.0 dibutyl ether hexanediamine Ex. 8 tetramethyl-(A1) 4.0 dibutyl ether hexanediamine Ex. 9 tetramethyl- (A1) 8.0 dibutylether hexanediamine Ex. 10 tetramethyl- (A1) 10.0 dibutyl etherhexanediamine Ex. 11 tetramethyl- (A1) 20.0 dibutyl ether hexanediamineEx. 12 m-xylenediamine (B1) 5.0 xylene Com. trimethylenebis R^(A) is a5.0 xylene Ex. 1 (N-methyl- hetero-ring in piperidine) (A) Com.dimethylhexyl- only one N 5.0 dibutyl ether Ex. 2 amine atom Com.tetramethyl- R^(A) = methyl, 5.0 dibutyl ether Ex. 3 ethylenediamine L1= L2 = methylene, and p1 = p2 = p3 = 0 in (A) Com. hexamethylene- AllR^(A)s are 5.0 xylene Ex. 4 diamine hydrogen atoms in (A) Com.tetrabutyl- All R^(A)s are 5.0 dibutyl ether Ex. 5 hexanediamine butylgroups in (A) Com. m-phenylene- q1 = q2 = 0 in 5.0 xylene/DMF* Ex. 6diamine (B) Com. trimethylenebis R^(A) is a 4.0 xylene Ex. 7 (N-methyl-hetero-ring in piperidine) (A) Com. trimethylenebis R^(A) is a 1.0dibutyl ether Ex. 8 (N-methyl- hetero-ring in piperidine) (A) Com.hexamethylene- All R^(A)s are 1.0 dibutyl ether Ex. 9 diamine hydrogenatoms in (A) Com. m-phenylene- q1 = q2 = 0 in 1.0 dibutyl ether Ex. 10diamine (B) *Because of the solubility of m-phenylenediamine, thesolvent of Comparative Example 6 was a mixture of xylene 62 g/DMF 2 g.**The amine compounds used in Comparative Examples 8, 9 and 10 had toopoor solubility to prepare homogeneous compositions.

Among the above, homogeneous compositions were selected. Eachhomogeneous composition was spin-coated on a 4-inch silicon wafer of 0.5mm thickness (under the conditions of 500 rpm/5 seconds and thereafter1000 rpm/20 seconds). The compositions were then converted intosiliceous substances under the following conditions.

Conversion condition A: settled for 24 hours under environmentalconditions (room temperature, relative humidity: 40 to 55%);

Conversion condition A3: settled for 3 days under environmentalconditions (room temperature, relative humidity: 40 to 55%);

Conversion condition B: subjected to high-temperature and high-humiditytreatment for 60 minutes at 40° C. and a relative humidity of 95%;

Conversion condition C: fired for 2 hours on a hot-plate at 300° C.;

Conversion condition D: fired for 15 minutes on a hot-plate at 80° C.and then settled for 24 hours under environmental conditions (roomtemperature, relative humidity: 40 to 55%);

Conversion condition E: subjected to high-temperature and high-humiditytreatment for 10 minutes at 40° C. and a relative humidity of 95%; and

Conversion condition F: treated with steam heated at 200° C. for 1 hour.

Since the compositions of Comparative Examples 8 to 10 could not formuniform films, it was impossible to subject them to the following WERevaluation. Although very small amounts of amine compounds were added,they were insufficiently dissolved in the compositions of ComparativeExamples 8 to 10. This means that solvents are restricted if aminecompounds out of the scope of the present invention are used.

With respect to each composition, an IR spectrum was measure before andafter the conversion so as to evaluate the degree of conversion into asiliceous substance. The IR spectrum of siliceous substance obtained bythe conversion generally had absorption peaks assigned to Si—O bondapprox. at 1030 cm⁻¹ and 450 cm⁻¹, assigned to Si—C bond approx. at 1270cm⁻¹ and 780 cm⁻¹ and assigned to C—H bond approx. at 2970 cm⁻¹. On theother hand, the IR spectrum before the conversion generally hadabsorption peaks assigned to N—H bond approx. at 3350 cm⁻¹ and 1200 cm⁻¹and assigned to Si—H bond at 2200 cm⁻¹. If the composition is convertedinto a siliceous substance, the former absorption peaks appear while thelatter peaks disappear. Siliceous films formed from all the compositionsof Examples 1 to 11 exhibited IR spectra in which the peakscharacterizing polysilazane disappeared, and thereby it was verifiedthat the compositions of the present invention were completely convertedinto siliceous substances. However, films formed from all thecompositions of Comparative Examples exhibited IR spectra in which thepeaks assigned to N—H bond were observed approx. at 3350 cm⁻¹ and 1200cm⁻¹, and thereby it was found that they were not completely convertedinto siliceous substances.

The compositions were subjected to the WER evaluation in the followingmanner. Before and after the silicon wafer coated with each converted orunconverted composition was immersed in 0.5% aqueous hydrofluoric acidsolution for 1 to 5 minutes, the thickness of the siliceous film wasmeasured by means of an ellipsometer and thereby the thicknessdecreasing rate per minute (in terms of Å/minute) was calculated todetermine a WER value. The results were as set forth in Tables 2 and 3.Small WER values in Tables mean that the siliceous films giving thosevalues less undergo etching and accordingly have high density.

TABLE 2 WER (Å/min.) Conversion Conversion condition A condition B Ex. 11027 712 Ex. 2 960 832 Ex. 3 4074 980 Ex. 4 996 815 Ex. 5 3471 2662 Ex.8 2522 807 Com. Ex. 1 2403 1236 Com. Ex. 2 6078 5765 Com. Ex. 3 57236066 Com. Ex. 4 7797 4417 Com. Ex. 5 5421 4961 Com. Ex. 6 5884 5739 Com.Ex. 7 4204 2206 Com. Ex. 8 unmeasurable Com. Ex. 9 unmeasurable Com. Ex.10 unmeasurable

TABLE 3 Conversion condition WER (Å/min.) Ex. 6 C 533 Ex. 7 B 1256 Ex. 8D 1028 Ex. 9 E 2337 Ex. 10 F 299 Ex. 11 C 388 Com. Ex. 8 unmeasurable

As for the silicon wafers coated with the films obtained under theconversion condition A3, the hardness thereof was measured by means of ananoindenter hardness tester. The results were as set forth in Table 4.

TABLE 4 Martens Young's Hardness hardness modulus (Gpa) (Gpa) (Gpa) Ex.1 4.57 2.49 42.50 Ex. 2 4.97 2.76 47.78 Ex. 12 4.69 2.87 51.75 Com. Ex.1 3.65 1.92 36.46 Com. Ex. 5 3.35 1.54 23.22

The invention claimed is:
 1. A polysilazane-containing compositioncomprising a polysilazane compound, an amine compound represented by thefollowing formula (A):

(wherein each R^(A) independently represents hydrogen or a hydrocarbongroup of C₁ to C₃ under the condition that two R^(A)s connecting to thesame nitrogen atom are not hydrogen atoms at the same time, each of L¹and L² independently represents, CH₂, —NR^(A1)— (in which R^(A1) ishydrogen or a hydrocarbon group of C₁ to C₄) or —O—, where at least oneof L¹ and L² is chosen from CH₂ each of p1 and p3 is independently aninteger of 0 to 4, and p2 is an integer of 1 to 4), and, a solventcapable of dissolving said polysilazane compound and said aminecompound, where the solvent is selected from a ketone whose vaporpressure at 20° C. is 0.8 kPa or less.
 2. The polysilazane-containingcomposition according to claim 1, wherein said solvent further comprisesa second solvent selected from the group consisting of decane,p-menthane, dipentene, dibutylether and mixtures thereof.
 3. Thepolysilazane-containing composition according to claim 2, wherein saidsecond solvent is decane.
 4. The polysilazane-containing compositionaccording to claim 2, wherein said second solvent is p-menthane.
 5. Thepolysilazane-containing composition according to claim 2, wherein saidsecond solvent is dipentene.
 6. The polysilazane-containing compositionaccording to claim 2, wherein said second solvent is dibutylether. 7.The polysilazane-containing composition according to claim 1, whereinsaid solvent further comprise a second solvent selected from ethers. 8.The polysilazane-containing composition according to claim 1, whereinsaid solvent further comprise a second solvent selected from etherswhose vapor pressure at 20° C. is greater than 0.083 kPa.
 9. Thepolysilazane-containing composition according to claim 1, wherein saidsolvent further comprise a second solvent selected from saturatedhydrocarbon compounds.
 10. The polysilazane-containing compositionaccording to claim 1, wherein said solvent further comprise a secondsolvent selected from alicyclic hydrocarbon compounds.
 11. Thepolysilazane-containing composition according to claim 1, wherein saidpolysilazane compound is perhydropolysilazane.
 12. A process for forminga siliceous film, wherein the polysilazane-containing compositionaccording to claim 1 is coated on a substrate and then converted into asiliceous film.
 13. The process according to claim 12 for forming asiliceous film, wherein the conversion into a siliceous film isperformed under the conditions of a temperature of 100° C. or below anda relative humidity of 40 to 95%.
 14. A siliceous film formed by theprocess according to claim 12.